Manufacture of reactive forms of cellulose and the like



Patented-Jan. 20, i942 Q MANUFACTURE OF REACTIVE FORMS OF CELLULOSE AND THE LIKE Clemmy 0. Miller, Milwaukee, Wis., and Arthur E. Siehrs, Chicago, Ill., assignors to North American Rayon Corporation, New York, N. Y., a. corporationof Delaware No Drawing. Original application January 30,

1932, Serial No. 589,974. Divided and this application March 29, 1939, Serial No. 264,859

26 Claims.

This invention relates to the manufacture of reactive forms of cellulose and the like; and refers more particularly to improved processes of treatment whereby chemical and/or physical changes are produced in the base materials so that their rates of reaction with reagents. for

producing derivatives therefrom are markedly increased.

A primary object of the invention is to .obtain a reactive form of cellulose from which viscose, cellulose esters, and cellulose ethers can be obtained more readily and more conveniently than by the methods that are now being used. The

general methods to be presently described for manufacturing reactive forms of cellulose are ap plicable to-carbohydrates of similar constitution, such as starch and other polysaccharides and the invention comprises the treatment of these substances when i the application of the improved process is found to be of advantage. It is there fore to be understood that where the term "cellulose" is used it is intended to cover the treatmeat of similar materials whenever found advantageous.

The activation of cellulose heretofore has been effected by treatment with aqueous solutions of caustic soda to convert it into what isgenerally called soda cellulose, it being usualiy necessary to allow the treatment to continue for periods varying from 12 to '12 hours to obtain a sumclently active alkali cellulose to react readily with carbon disulflde toform viscose compositions utilized in the manufacture of silk substitutes. The ageing of the soda cellulose requires varying periods of time, depending upon, such' factors as the source of the cellulosic material such as cotton or cotton llnters. wood pulp, linen rags, et-cetera, and it is obvious that a process whereby the cellulose could be rendered suflicientlyreactive so that. it will react with, carbon disulfldewithout employ a certain amount of sulfuric acid as ameans of assisting in the removal of water from the reacting substances. The present process, as will be presently explained, offers a simpler method for the production of cellulose acetate due to the greater reactivity of the cellulose produced. This applies to the manufacture of all the cellulose esters.

The above illustrations will suflice to show that cellulose of greater reactivity than is found in th types produced by caustic soda treatment will find important uses in the cellulose industries.

In its most general and preferred embodiment the present invention comprises the production of reactive cellulose by treatment of cellulose ma-... .terials with ammonia alone or in combination with various metals, amides, ,imides, oxides, hy-

droxides and salts of metals and organic ammonia derivatives, and ammonium derivatives such as amines, salts of amines and quaternary ammonium salts. 'I'heammonia may be utilized either in liduid or gaseous phase and in the liquid phase may be mixed with certain alcohols,

hydrocarbons, ethers, aldehydes, acid amides,

ketones, acids, esters, nitrobenzene, et cetera, according. to their solubility, and in the gaseous phase may be diluted with such gases as nitrogen, hydrogen netc. The various modifications of treatment comprised within the scope of the in- .vention will be'set forthin'detail in the following specification. I

In one specific embodiment the invention comprises the manufacture of reactive cellulose by pretreatment with caustic soda'and ageing would be of great 'value in the manufacture of viscose. In the manufacture of cellulose. acetate, taking it as anexample of the manufacture of cellulose esters, cellulose byv one process is treated with a mixture of glacial acetic acid'and acetic anhydride. During the reaction apart of the acetic anhydride is converted into acetic'acid. The discoveryof aim of cellulose that will react directly with appropriate substances to give'cellulose acetate without degradation of apart of it to some form that will not react with cellulose,

would be of great value in the manufacture of cellulose acetate. In the ordinary methods of manufacture of cellulose acetate it is customary to treatment of cellulosic materials with anhydrous ammonia. When we wish to refer to an anhydrous ammonia that has been treated to remove I the water that is present as an impurity bysome special process, we will designate it as dry an.-

hydrous ammonia or dried anhydrous ammonia. 1

We shall refer to the reactive product obtained when cellulose is steeped in anhydrous ammonia or exposed to ammonia gases or vapors, as ammonia cellulose. -We refer to it in this way to designate it from other more reactive forms of cellulose that we shall describe later. We do not infer by the term that it is a salt of cellulose or that the nitrogen content of the cellulose is even increased. It is somewhat analogous to the term soda cellulose, which refers to cellulose that has been treated with strongcaustic soda. By ammonia cellulose, we mean cellulose that has been brought into contact with anhydrous ammonia, or ammonia gas'or vapors. The cellulose used in thepreparation of ammonia cellulose is preferably cellulose that has been dried by exposure to the air or subjected to any convenient drying process that decreases its moisture content to some very low value, as 0.3% or less. ture content of cellulose dried by exposure to air varies with the humidity of the air. It may be as high as 8% or as low as 0.3%. We shall refer -to cellulose that has been dried by exposure to air as air-dry cellulose or air-dried cellulose and to cellulose that has been subjected to any convenient drying process, such that its moisture content is less than 0.3%, as dry cellulose or dried cellulose.

As an example of the method of operation when preparing ammonia cellulose we cite the. following: Ten parts of cellulose, as cotton, cotton linters, wood pulp, et cetera, are placed in a container well insulated from heat, and approximately 50 parts of anhydrous ammonia are drawn onto the cellulose, The ratio of cellulose it from any liquid that is adhering to it, as by.

evaporation, pressing, reduced pressure, heat, et cetera, or any combination of these. monia cellulose prepared in this way can be immediately converted (without ageing) in-to viscose by treatment with carbon disulflde and sodi- The moisminutes. By increasing the temperature and correspondingly increasing the pressureto maintain the ammonia as a liquid, the time required for the desired reaction may be shortened.

Furthermore, we have found that the form in which the cellulose exists is not a limiting factor for the production of ammonia cellulose. For example, it may be in a loose powdery form as wood pulp, fine form like cotton linters, it may be a thread or filament, or it may be woven, knitted, or fabricated in any way. The important factor is that it be sumciently loose to permit penetration by the liquid ammonia and sufficient time ture which accounts for its increased reactivity.

In support of the former explanation, cellulose is an acid in anhydrous ammonia, which would The amum hydroxide in aqueous solution or. into cellulose esters or cellulose ethers by treatment with the appropriate substances. We will set forth the details of these processes later.

In the manufacture of ammonia cellulose, we have found that it is convenient to carry out the steeping of the cellulose at approximately the boiling point of anhydrous ammonia at atmospheric pressure, which is about '28 F. We have found that treatment of cellulose with anhydrous ammonia at higher temperatures up to a maximum of approximately 266 F., or at lower temperatures down to a minimum of approximately 10,7.2 F., or pressures up to approximately 115 atmospheres or down to atmosphere still gives ammonia cellulose. The cellulose used may be 'dried cellulose or air-dry cellulose as previously defined, and the anhydrous ammonia may be commercial anhydrous ammonia or dried anhyexcess of ammonia present. We have been able to obtain ammonia cellulose under all conditions where the cellulose comes into contact with the anhydrous ammonia and becomes saturated with make salt formation .a possibility. It is'well known to those familiar'with the properties of solutions of salts in liquid ammonia, that compounds are ammonolyzed in anhydrous ammonia, though to a less extent than they are hydrolyzed in water. Thus, the fact that the ammonium salt of cellulose cannot exist in water does not prove that the ammonium salt of cellulose ,cannot. exist in anhydrous ammonia.

We wish to point out that the properties of cellulose obtained in the way that we have described are profoundly different from cellulose that has been treated with mmonia water-or ammonium hydroxide. It is therefore a new product.

In another specific embodiment the invention comprises preparation of ammonia cellulose by treatment of cellulosic materials with ammonia gas.' In operations of this character we prefer to use finely separated air-dry cellulose which. has been rendered adsorbent by any convenient process. It is placed in a closed container and ammonia gas or vapor containing preferably less than 5% I water vapor isslowly led over it, preferably at superatmospheric pressure. We prefer to cool the container and not to allow the temperature of the material to go above 212" F. .The

lulose others by use of the appropriate chcm-" icals. The details of these methods will be set forth later.

We have found that dried cellulose and dry ammonia gas do not give ammonia cellulose as it. The time required for steepingdepends upon the degree of comminution of the cellulose, but seldom amounts; to more than 30 minutes;

While we have obtained ammonia cellulose that'is satisfactory in less time than 15 minutes, we believe 15 minutes is the minimum time for steeping. The ammonia cellulose obtained by allowing cellulose to steep in anhydrous am-' monia for six hours seems to have few advantages over ammonia cellulose obtained after 30 readily as air-dry cellulose and ammonia gas or vapor containing water vapor, preferably less than 5%. The presence of water in the fiber and the gas seems to favor the preparation of the ammonia cellulose. Dried cellulose can be used when the ammonia gflS'OI vapor contains water vapor. It is not necessary that there bea stream of gas owing over the cellulose; it is suflicient to have a continuous quantity of the gas incontactlwith the'cellulose. It will be obvious that cellulose which hasbeen rendered absorbent by any suitable process will take up ammonia faster than the ordinary or less absorbent varieties. v

Treatment under pressure with cooling seems tofavor the. rapid absorption of ammonia bycellulose. "When a highly absorbent cellulose is It may be an ammonium salt of cel- Ammoniacellulose obtained in this way An increase in temperature decreases the rate of absorption of ammonia by the cellulose; The

length of time required for obtaining a product having a maximum reactivity varies with the degree'of absorbency of the cellulose, the moisture content of the cellulose, the water content of the ammonia gas, the pressure of "the ammonia gas or vapor, the temperature at which the process is carried out, and the degree of comminution.

The properties of ammonia cellulose prepared in this way are essentially the-same as-the'properti'es of ammonia cellulose prepared by treatment with anhydrous ammonia. The form of the cellulose includes finely divided cellulose, flla-- merits, threads, woven or knitted or cellulose in any fabricated form.

In a further specific embodiment the invener, the sodium and the cellulosic product formed is minimally exposed to the moisture of the air.

* When the sodium is added, if water is present,

tion comprises the production of active cellulose V by treatment of cellulosic materials with. solu-' tions of alkali metals such as sodium, potassium, et cetera, in liquid ammonia.

- In the preparation ofreacti ve forms of cellulose bya process of this type, we prefer to use sodium,

and tocarry it out as'follows; ,We shall refer to the reactive form of cellulose formed in this way as sodium cellulose; -We shall discuss later the relation of the sodium to the cellulose. By

sodium cellulose we .mean' a cellulose product ob-.

tained by treating drycellulose suspended in .dried'anhydrous ammonia with any amount of sodium up to suchamount: that if any more; sodium is added, the anhydrous ammonia will' remain blue. Twenty-five parts of dried cellulose having a moisture content of 0.3% or less, may be placed in a container well insulated from heat.

The container must be constructed in such a;' way will react with theeellulose.

it will react first ith the water to form sodium hydroxide which is insoluble in anhydrous am-..

monia. After the water is used up the sodium prepared showing the rate of liberation of hydrogen with respect to moisture content of cellulose, it shows a sharp break where the-moisture content of cellulose becomes 0.3% or less. Ob-

fviously, the use of incompletely driedcellulose and incompletely dried anydrous ammonia in this process'is'not economical. I a

We have found that it is most'convenient to carry out the process at the temperature of boiling ammonia at. atmospheric pressure, which is about 28 F. However, we have found that the properties of the cellulosic product obtainedat 'higher temperatures, as 266 F., or lower temperatures, -l07.2 F., or at higher pressures, as'hlgh as 115 atmospheres,-or atlower pressures, as t;

atmosphere, do not differ essentially from. that prepared at 28 F. p

" Inour illustration, we have used the proportionsof 25 parts of cellulose toone part of sodium.

- We have tried other proportions of'cellulose and sodium as 4 parts of cellulose to 1 part of sodium, f

V and 10 partsof cellulose to 1 part of sodium.

The. reactivity of the sodium cellulose increases with' increasing sodium content and decreases that air cannot enter the system, but any. gas

no air is permitted to;nter

cellulose is present, the color is fleeting,-for the little water is required .to transform the small cellulose reacts with the'dissol'ved'metal to-"give hydrogen anda colorless solution.- The cellulose is not visibly dissolved in-the process}: The amount of hydrogen liberated under the condi} tions described is chemically equivalent to the amount of sodium added. We'preferto stir-while adding the sodium. Two hours arepgenerally required for this treatment; The time iyaries with the degree of comminution of the-cellulose;

the more finely divided the product, theshbiter i is the time required for treatment. Thereaction is complete when the blue colorisdischarged following the addition'of all 01' the sodium. The

cellulose product is separated from the anhydrous ammonia by any convenient process, as, evaporation, pressing, exposing to a reduced pressure,

warming slightly, or'any combination of'these.

The cellulosic product is then readyfor conversion into viscose by treatment with carbon-disulfide and caustic soda, or into cellulose esters and cellulose ethers by methods that will be described subsequently.

- We have found that it is of great importance to have the cellulose thoroughly dried, i.- e., a-

moisture content of 10.3% or less, to have the anhydrous ammonia or its vapors in the containwith decreasing sodium content. The proportions of cellulose to sodium shouldnot be such that the deep blue colorof the solution is not discharged '-.by the cellulose. For the preparation of viscose,

sodium cellulose prepared by treating 25 parts of cellulose with-l part of I sodium gives a satisfac- --tory viscose. For the} preparation of cellulose esters, the proportions ,of about 4110 1 seem tobe best. In the preparation of sodium cellulosehav- "ing a very low sodium content,'it isimportant that no water be presentin any form, for very amount of sodium into sodium hydroxide. ,A

mixture of cellulose and sodium hydroxidewould be obtained and not sodium cellulose, as we de.

fine it.

In the treatment of cellulosc ered by. the anhydrous ammonia toiinsureflall of little consequence. For example,the sodium may be added to the, anhydrous ammonia first and thelcellulos'e last. The form in which the cellulose is .treatedis of'littleconseqiience; It

-may be finely divided, or in the :form of filaments of threads, knitted, woven, or otherwise=fabricatedinto special forms.

We do'not know what takes place in thecellulose whenitischanged into sodium cellulose.

The transformation may be chemical and/or physical. Since cellulose is a weak acid in anhydrous ammonia, it is possible that sodium cellulose is asodium' salt of cellulose. We'llave some evidence that supports this explanation.

'Sinceit is known that salts are ammonolyzed in anhydrous ammonia though usually to a less anhydrous ammonia thoroughly dried,'and the. apparatus built in such a way that the cellulose,

'degree than they are hydrolyzed in water, there i is apossibility or its existence in anhydrous am monia. Sodium cellulose is profoundly different from the soda cellulose or alkali cellulose prepared by treating cellulose with a strong aqueous solution of sodium hydroxide such as 20% Or-' When a g.aph is v v with sacrum m I anhydrous ammoniathe cellulose should be covthe cellulose comingfinto contact wan the sodlum. Theorderin which cellulose, anhydrous ammonia, and sodium are brought together is i be prepared similarly by using any appropriate metal, or metals, provided that the metal is sufficiently soluble in anhydrous ammonia.

In a further specific embodiment the invention comprises the production of active cellulose by treatment of cellulose materials with ammonia and metal amides, imides or nitrides individually or in suitable combinations. As examples of compounds included in this class may be mentioned sodamide,potassium amide and the other amides of the alkali metals and such substances as barium imide, magnesium nitride, et cetera.

In conducting operations of this character we prefer for certain reasons to use potassium amide as follows: Three parts of dried cellulose is suspended in ten parts of dry anhydrous ammonia,

, removed by any convenient process and is freed and one part of potassium amide is added. It is allowed to stand for an hour, after which the cellulose may be separated from the adherin liquid by pressing, allowing time for evaporation, exposure to reduced pressure, or slight warming. It is then ready'for conversion into' cellulose products.

As in the case of thepreparation of sodium cellulose, moisture is an important factor and must be excluded from the materials used and the containing vessel. The container must be constructed to prevent the entrance of air carrying moisture. Even though a reactive product.

maybe -obtained using cellulose that has been incompletely dried or wet ammonia, it is generally not economicalto carry it out in this way.

The success of the reaction is not dependent upon any particular temperatures and pressures, and therefore the choice of temperature and pressure is made on the basis of convenience.

= We have found the temperature of boiling ammonia at atmospheric pressure to be the most convenient. When we use sodamide, we have found it more convenient to carry out the process at 25 C, and at the pressure of anhydrous ammonia at that temperature. The ratio of amounts of potassium amide to cellulose used' Y may vary considerably and still give a reactive material. A We have not found it advantageous to increase the amount of potassium amide beyond the point where theratio of amounts of potassium amide to cellulose is greater than 1.

ma further specific embodiment the invention comprises the production'of active cellulose e In applying this modification of the process of the invention to practice we may proceed as follows: Ten parts .of air-dry cellulose is placed in a suitable container and 50 parts of com} mercial anhydrous ammonia is drawn onto it. Ten parts of ammonium chloride is added to the cellulose and anhydrous ammonia. It is allowed to stand for six hours. The cellulose is 15' the process at'the' boiling point of ammonia at In place of the from any adhering liquid by being subjected to pressing, evaporation, exposure to reduced pressure, slight warming or any combination of these. -It is then ready for use. We have not found moisture to interfere materially in the successful preparation of this reactive form. The process is carried out most conveniently at the boiling point of anhydrous ammonia at atmospheric pressure, which is about -,28 F. The order of combination of the materials may be changed without serious consequence, as for example, the ammonium chloride may be added to the anhydrous ammonia and the cellulose added last. The length of time allowed for steeping may vary and still give a reactive product. The ammonia may be allowed to evaporate spontaneously instead of being separated from the ammonia mechanically. The cellulose may .be in ("a finely divided state, or as filaments,

threads, or fabricated into a cloth. The method used in-treating cellulose with other ammonium salts or with the organic amides and ureides is essentially the same as for ammonium chloride.

In a further specific embodiment the invention comprises the treatment of cellulosic materials for the production of active cellulose with liquid ammonia, organic amines and/or substituted ammonium salts. For example, primary, secondary or tertiary amines may be used such as ethylamine, dimethylamine, tripropylamine, ethylene diamihe, respectively, or the salts and hydroxides or compounds such as tetraethyl ammonium chloride, or tetraethyl ammonium hydroxide.

In the case of triethyl amine the preparation of active cellulose is readily' carried out by adding one part of triethyl amine to four parts of dry cellulose in fifty parts of dried anhydrous ammonia at -28 F. It is not necessary that the cellulose and ammonia be dried. We have found it most convenient to carry out the preparation at -28 F.; however, other combinations of temperature and'pressure give satisfactory results. The time required is less than two hours. ,The cellulosic product may be recovered by any convenient process, by evaporation, pressing, ex-' posure to reduced pressure, slight warming, or any combination of these.

In a further specific. embodiment the invention comprises the production of active cellulose by the treatment of cellulosic materials with ammonia and metal oxides such as, for example, cupric oxide, silver oxide, etc. In the case of metals of the alkaline earth group, their hydroxides may be employed with proper adjustment of the treating conditions.

In illustrating the method of preparation of active cellulose according to this methodQwe shall cite a case in which cupric oxide is used.-

To 4 parts of dried cellulose is added 50 parts of dried anhydrous ammonia and 1 part of cupric ,oxlde. The mixture is allowed to stand for about six hours, after which time the cellulose is separated from the anhydrous ammonia and the excess cupric oxide by any convenient process,

, such as, filtration and pressing; orthe ammonia may be allowed to evaporate oil, leaving the excess copper oxide with the cellulose.

We have found it satisfactory to use air-,dry cellulose and commercial anhydrous ammonia, although we prefer to use dried cellulose and dried anhydrous ammonia. Asin previous cases, we have found it most convenient to carry out ,aavasae atmospheric pressure, which is 28 F., although the temperature and pressurev can be altered widely without affecting the reaction.

, It is possible to vary the amount of cupric oxide used for a given amount of cellulose, and still obtain a reactive form of cellulose.

length of time required for steeping the cellulose depends upon the substance or substances used with the anhydrous ammonia and the degree of comminutlon of the cellulose. The meth- 0d for converting cellulose into a more reactive form by usingoxides other than cupric oxide and by hydroxides, is essentially the same as that given for cupric oxide. r

The modifications of the process using liquid ammonianthus far described may be employed when the liquid ammonia is substantially pure except for small amounts of water or when the ammonia is mixed with or in solution with various other solvents, for instance, with alcohols, hydrocarbons, ethers, aldehydes, ketones, acids, esters, acid amides, nitrobenzene; et' cetera.

, 7 Two parts "of cellulose was placed in a suitable The ' cellulose content of the solution 7%.

container, and iiftyparts of anhydrous ammonia was drawn onto it. -After letting the mixture stand at about -28 F. for 15 minutes, the 'ammonia cellulose was removed from the anhydrous ammonia, pressed, and finally subjected to a reduced pressure of about one pound per'square' was allowed to stand at 64 F. for 24 hours. After e use of these additional materialsis optional and contingent upon a number of factors and depends in,

general upon whether improved results are obtained by their use. The order'in whichithe cellulose, anhydrous. ammonia, inorganic :materials and'derivatives of ammonia, and the organic materials arecombined, maybe varied since the successful preparation of the reactive forms is not dependent upon any one order of combination. We are not'certain as to whether the prop ertiesof the reactive forms of cellulose prepared in the presence or the organic substances is idenforms or cellulose may be advantageously prepared in this way. 1 I s In the treatment of cellulose with ammonia gas or ammonia gas and water vapor to form a more-reactive form, we have found that gases or with the ammonia ,or the ammonia and water vapor without substantially inhibiting the formation of reactive forms. We do not know whether the reactive forms of cellulose prepared in the presence of such vapors are identical with the reactive forms of cellulose prepared with am-f monia gas alone, or ammonia and. water vapor,

. but have noted that they possess increased activity and that in some instances benefits are derived by the addition of neutral or diluent gases.

We have set forth various methods for the converting of cellulose-into forms that are more reactive towards various chemicals, as carbon disulfide andcaustic soda: and acids, acid anhydrides. acid halides, salts of-acids. and mixtures of anv-of these. Our investigations on starch, regenerated cellulose by viscousprocess,

and other polysaccharides have rcvealed'that they may be likewise converted into more re- I 1 tion, but we prefer to use the 8% ,solution. We tical with the ones that are prepared in their 7 absence, "or not, but have-noted that activated the excess carbon disulflde was removed by vblow- 1 ing air through'it, it was filtered, and set aside to mature at 64 F. The maturing process .was followed by occasional determinations of the salt number and viscosity.

1While we prefer to use'a'ir-dry cellulose ,and anhydrous ammonia, we have found that'fdried cellulose and dried anhydrous ammonia will'also give satisfactory results. We have found-that it is important to have the cellulose free from excess :ammonia,since its presenceleads to unnecf essary decomposition of the carbon" Ldisulflde.

The cellulose' content of the viscose solution is determined by the use to whiclrthe viscose; will be put and can be varied by using differentv'olumes of 8% sodium hydroxide solution. It'is possible to use other strengths of sodiumhydro'xide soluhave observed that the viscose prepared by our method matures faster, thatis, the salt number and viscosity of the viscose changes to the salt vapors; as nitrogen, hydrogen, hydrocarbons,

ethers, amines, et cetera, may be incorporated sulated from heat,and fifty parts of dried anhydrous ammonia was drawn onto it. One part of prepared by the methods nowin use.

' Sodium cellulose may be made andconverted .into viscose in the following way: Seven partsof dried cellulose was placed'in a container wellin-' sodium was added inseveral portions, and the reaction mixture was. allowed to stand for twohours after the addition of thelast portion of sodium. The sodium cellulose was removed from the anhydrous ammonia, pressed, and exposed parts of carbon disulfide for'twohours, after activeforms by treatment with anhydrous ammonia under the conditions described for cellulosejwehave found that the properties and uses of these more reactive forms are comparable to the properties and active forms of cellulose.

We have, stated previously that these reactive forms of cellulose can be used in the manufacture of viscose and cellulose esters. We shall cite examples illustrating how cellulose can be converted into viscose and cellulose esters, using the reactive formsthat we have described as intermediate products.

uses of .the more re which 28 parts of 8% water solution of sodium hydroxide was added, with thorough mixing.

This gives aviscose solution having a cellulose content of about 7%. The viscose is allowed to stand at 64 F. for 24 hours. It is filtered in any convenient way, and air is blown through itto remove the excess carbondisulfide. It is then ready to be set for maturing.

Although air-dry cellulose and commercial anhydrous ammonia can .be used, we prefer to use dried cellulose and dried anhydrous ammonia,

for it is more economical'with; respect to the sodium; The excess. of ammoniashouldbe removed since it decomposes some ofthe carbon. disulflde. As inthe case of viscose prepared from ammonia cellulose, the cellulose content can bernadeof the strength desired byusing the proper amount of 8% sodium hydroxide. The strength of the sodium hydroxide can beva'ried from We shall cite the preparation of cellulose acetate as an example of the use of our reactive forms of cellulose in the preparation of cellulose esters. For the preparation of the sodium cellulose for use in the formation of cellulose acetates, we prefer to treat 4 parts of dried cellulose in 50 parts of dried ammonia with 1 part of sodium. To one part of this sodium cellulose is added about 40 parts of acetone and 30 parts of acetyl chloride.

The reaction mixture iswarmed to 122 1''. for one hour and then allowed to cool to roomtemperature.

, can be used. The product obtained by this medium is essentially the same-as the product obtained when acetone is used as the reaction medium. .The cellulose acetate is precipitated by the addition of water or ether. It is soluble in chloroform and acetone. I

While we have specified the manufacture of cellulose acetates from sodium cellulose, we may form cellulose acetates by reaction with ammo nia cellulose. We include cellulose nitrate as one of the cellulose esters that can be prepared in this way. While air-dry cellulose and commercial anhydrous ammonia can be used, we prefer to use the dried materials because the sodium is used more economically on account of none being needed to react with water. Varying amounts of sodium can be used, up to the proportionsof 2 parts of cellulose to 1 part of sodium. The acetate content of the cellulose acetate produced varies with the sodium content of the sodium cellulose. We have the various examples given, it is to be understood that these proportions may be varied widely within the contemplation of this invention and without departing from the scope thereof by those skilled in this art. We do not desire to limit ourselves in any way to the exact proportions specified, as they are merely illustrative of conditions with which we have had success and are not to e be construed as limiting factors.

-This is a division of our'co-pending application Serial No. 589,974, filed January 30, 1932.

We claim: 1. In the preparation of reactive carbohydrates, the improvement which comprises treating a carbohydrate with an earth alkali metal dissolved in liquid, anhydrous ammonia.

2. In the preparation of reactive carbohydrates, the improvement which comprises treat,- ing a carbohydrate with calcium metal dissolved:

. in liquid, anhydrous ammonia.

3. In the preparation of reactive carbohydrates, the improvement which comprises treating a carbohydrate with barium metal dissolved in'iiquid, anhydrous ammoniaw r 4., In the preparation 01 .reactive carbohydrates, the improvement which comprises treat- It is allowed to stand for three hours. The reaction mixture is ing a carbohydrate at a temperature of about -28 F. with an earth alkali metal dissolved in liquid, anhydrous ammonia.

5. In the process of producing. carbohydrate derivatives which comprises treating a carbohydrate with an earth alkali metal dissolved in liquid, anhydrous ammonia to form a modified carbohydrate substantially separating said ammonia from said modified carbohydrate and subsequently causing said modified carbohydrate to react with an esterifyin'g agent to form a carbohydrate ester.

6. In the preparation of reactive cellulosic materials, the improvement which comprises treating a cellulosic material with an earth alkali metal dissolved in' liquid, anhydrous ammonia.

7. In the preparation of reactive cellulosic materials, the improvement which comprises treatl ing a cellulosic material with calcium metal dissolved in liquid,- anhydrous ammonia.

s 8. In the preparation of reactive cellulosic materials, the improvement which comprises treating a cellulosic material with barium metal disof about 28 F. with an alkali earth metal dissolved in liquid, anhydrous ammonia.

11. As a new article of manufacture an anhydrous, reactive earth alkali metal carbohydrate. v

12. As a new article of manufacture an anhydrous, reactive earth alkali inetal cellulosate.

13. As a new ,article of manufacture an anhydrous, reactive barium carbohydrate.

14. As a new article of manufacture an an-' hydrous, reactive barium cellulosate.

15. In the preparation of reactive carbohydrates, the improvement which comprises treating acarbohydrate at a temperature below -28 F. with an earth alkalimetal dissolved in liquid, anhydrous ammonia.

.16, In the preparation of reactive carbohydrates, the improvement which comprises treating'a carbohydrate at a temperature below -28 F. with calcium metal dissolved in liquid, an-

hydrous ammonia.

17. In the preparation of reactive carbohy:

drates, the improvement which "comprises treating a carbohydrate at a temperature below --28 F. with barium metal dissolved in liquid, anhydrous ammonla.

18. In the preparation of 'reactive cellulosic materials, the improvement which comprises treating a cellulosic. material at a temperature below -28-. F. with an earth alkali metal dissolved in liquid, anhydrous ammonia.

19; In" the preparation of reactive cellulosic materials, the improvement which comprises treating a cellulosic material at a temperature below -28 F. with calciummetal dissolved in liquid, anhydrous ammonia.

20. In the preparation of reactive cellulosic materials, the improvement 'which comprises.

treating a cellulosic material at a temperature below -28 F. with barium metal dissolved in liquid, anhydrous ammonia.

i 21. In the process of producing carbohydrate derivatives, the improvement which comprises treating a carbohydrate with an earth alkali metal dissolved in liquid, anhydrous ammonia to form a modified carbohydrate, substantially sep arating said ammonia from said modified carbohydrate ahd subsequently causing said modified carbohydrate to react with an esteriiying agent in a medium comprising an inert, organic solvent to form a carbohydrate ester.

'22. In the process of producing carbohydrate derivatives, the improvement which' comprises treating a carbohydrate at a temperature below -28 F. with an earth alkali metal dissolved in liquid, anhydrous ammonia to form a modified carbohydrate, substantially separating said ammonia from said modified carbohydrate and subsequently causing said modified carbohydrate to cellulosic materials, the improvement which comprises treating a cellulosic material at a temperature below 28 F. with an earth alkali metal dissolved in liquid, anhydrous ammonia to form a modified cellulosic material, substantially separating said modified cellulosic material from said ammonia and subsequently causing said modified cellulosic material to react with an esterifying agent to form an ester of said cellulo losic material.

react with an esterifying agent to form an ester of said carbohydrate. I

23. In the process of producing carbohydrate 1 1 derivatives, 'the improvement which comprises treating a carbohydrate at a temperature of about 28 F. with an earth alkali metal dis-' solved in liquid, anhydrous ammonia to form a modified carbohydrate substantially separating-v .said ammonia from said'modified carbohydrate and subsequently causing said modified carbohydrate toreact with an esterifying agent to form an ester of said carbohydrate. f

24. In the process of producing derivatives of 25. In the process of producing derivatives of cellulosic materials, the improvement which comprises treating a cellulosic material at a temperature of about 28 F. with an earth alkali metal dissolved in liquid, anhydrous ammonia to form a modified cellulosic material, substantially separating said modified cellulosic material from a said ammonia and subsequently causing said -modified cellulosic material to react with an ing an inert, organic solvent to form an ester or said cellulosic material. I

\ CLEMMY O. MILLER. AR'IHUR E. SIEHRS. 

